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Photodynamic therapy for pythiosis
Author(s) -
Pires Layla,
Bosco Sandra de M. G.,
da Silva Junior Nelson F.,
Kurachi Cristina
Publication year - 2013
Publication title -
veterinary dermatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.744
H-Index - 60
eISSN - 1365-3164
pISSN - 0959-4493
DOI - 10.1111/j.1365-3164.2012.01112.x
Subject(s) - photodynamic therapy , in vivo , photosensitizer , amphotericin b , in vitro , porphyrin , microbiology and biotechnology , biology , pathology , medicine , chemistry , antifungal , biochemistry , organic chemistry
Background – Pythiosis is a life‐threatening disease caused by Pythium insidiosum . Photodynamic therapy (PDT) is an alternative treatment to surgery that uses the interaction of a photosensitizer, light and molecular oxygen to cause cell death. Objectives – To evaluate the effect of PDT on the in vitro growth of P. insidiosum and in an in vivo model of pythiosis. Methods – For in vitro studies, two photosensitizers were evaluated: a haematoporphyrin derivative (Photogem ® ) and a chlorine (Photodithazine ® ). Amphotericin B was also evaluated, and the control group was treated with sterile saline solution. All experiments (PDT, porphyrin, chlorine and light alone, amphotericin B and saline solution) were performed as five replicates. For in vivo studies, six rabbits were inoculated with 20,000 zoospores of P. insidiosum , and an area of 1 cm 3 was treated using the same sensitizers. The PDT irradiation was performed using a laser emitting at 660 nm and a fluence of 200 J/cm 2 . Rabbits were clinically evaluated daily and histopathological analysis was performed 72 h after PDT. Results – For in vitro assays, inhibition rates for PDT ranged from 60 to 100% and showed better results in comparison to amphotericin B. For the in vivo assays, after PDT, histological analysis of lesions showed a lack of infection up to 1 cm in depth. Conclusions and clinical importance – In vitro and in vivo studies showed that PDT was effective in the inactivation of P. insidiosum and may represent a new approach to treating pythiosis.